Application of trivalent cation cross-linked quorum quenching beads for biofouling mitigation and phosphorus removal in a membrane bioreactor

This study applied quorum-quenching cell-entrapping beads (QQ-CEB) to mitigate membrane fouling and enhance phosphorus removal in a membrane bioreactor (MBR). Instead of suspending QQ-CEB in the MBR, immobilising it on a recovery net maintained the effluent total phosphorus removal at approximately 50%. It extended the system's operational period by about 2.2 times compared to a conventional MBR. Membrane fouling mitigation was attributed to quorum-quenching activity, reducing microbial products accumulated on the membrane surface by 28-47%. Signalling molecule analysis further confirmed that the QQ mechanism alleviated biofouling by inhibiting microbial quorum sensing. The Fe³⁺-cross-linked QQ-CEB exhibited an operational lifespan 1.53 times longer than that of the Ca²⁺-cross-linked QQ-CEB in the MBR process. Microbial community analysis of the Fe³⁺ QQ-CEB indicated that the intrusion of external microorganisms was effectively suppressed, thereby maintaining a stable microbial community within the beads.